Authenticate Internal Request using Client Token

| Q | A
| ----------------- | ---
| Bug? | no
| New Feature? | yes
| Framework | Laravel
| Framework version | 5.5.18
| Package version | 2.0.0-alpha1
| PHP version | 7.0.22

#### Actual Behaviour

I am using Laravel with Passport authentication. Some of my APIs needs client authentication. I am not able to make use of the internal request to consume these APIs as I am not able to authenticate using my client token.

#### Expected Behaviour

Same like authenticating the user, there should be a way to authenticate via the client.

Start by examining how internal requests authenticate users in the Laravel and Lumen API package, then compare that flow with Laravel Passport client-token authentication. Done means an internal request can authenticate with a client token and consume APIs that require client authentication, with coverage for the new behavior.

Written by the indexing model from the issue text.